[DiapDealer]

That's probably why Debian Unstable hasn't updated from 2.0.1 to 2.0.2. One could always try to build Sigil 2.0.2 against Qt5 (using -DUSE_QT5=1 in the original cmake configuration) to rule out Qt6 as the culprit.

Or.... you could just add the qt6-svg package, which is a runtime dependency of Sigil, to make the icons appear. A Qt SVG package is the first one mentioned in the latest Sigil Linux Qt6 build instructions.

As for PageEdit not launching, that's probably due to the Sigil launch script (/usr/local/bin/sigil) trying launch a repo installed version of PageEdit (a Qt5 version) that has diddled the launch script slightly. I would recommend using repo-supplied versions of both, or custom built versions of both (using the same Qt version) rather than some mixture of both.